1. Field of the Invention
The present invention relates to gasoline compositions for reducing intake valve deposits in port fuel injected engines.
2. Background
Gasoline compositions have traditionally been formulated to improve the performance of carburetor and throttle body injected engines. Beginning in about 1984, electronic port fuel injected engines were commonly introduced by automobile manufacturers. Shortly thereafter, in about 1985, problems began to be reported with intake valve deposits in electronic port fuel injected engines characterized by hard starting, stalls, and stumbles during acceleration and rough engine idle.
Accordingly, it would be desirable to have fuel compositions which reduced or eliminated such undesirable intake valve deposits in electronic port fuel injected engines. Also, since some carburetor and throttle body injector engines will still be in use for the foreseeable future, it would be desirable if such fuels could also be compatible with these engines. Intake valve detergency is generally defined by the BMW NA standard of intake valve cleanliness for unlimited mileage, which is an established correlation of good driveability with average intake valve deposit weight of 100 milligrams/valve or less.
Oil-soluble polyalkylene polyamines containing an olefinic polymer chain are known to improve detergent properties of fuels used in carburetor and throttle body type engines. These polyalkylene polyamines, particularly when used at high concentrations, can result in valve sticking and an increase in octane requirement. Various materials have been added to these polyalkylene polyamines to improve their performance. U.S. Pat. No. 5,006,130, issued April 9, 1991, discloses as a gasoline additive (a) polyalkylene polyamine and (b) at least one component selected from (i) a polymer of a C.sub.2 to C.sub.6 monoolefin, (ii) a copolymer of a C.sub.2 to C.sub.6 monoolefin, (iii) the corresponding hydrogenated polymer of copolymer, (iv) an oil soluble poly(oxyalkylene) alcohol, glycol or polyol or a mono or di ether thereof.
Hydrocarbylpoly(oxyalkylene)aminocarbamates have been disclosed in U.S. Pat. No. 4,197,409, issued Apr. 8, 1980 and U.S. Pat. No. 4,191,537, issued Mar. 4, 1980, as useful as deposit control additives which effectively control deposits in intake systems (carburetor, valves, etc.) of engines operated with fuels containing them, but which do not contribute to the combustion chamber deposits which cause increased octane requirements.
Mannich polyamines comprising the condensation product of a high molecular weight alkyl-substituted hydroxy aromatic compound, an amine which contains an amino group having at least one active hydrogen atom, and an aldehyde have been disclosed in U.S. Pat. No. 4,231,759, issued Nov. 4, 1980, as useful for importing detergency properties to an automotive fuel in order to keep intake valves clean.